The invention relating to such articles, particularly to such article provided along respective thigh-surrounding zones with a plurality of rubber threads as elastic members associated with leg-holes and the invention relating to a process for placement of these rubber threads are disposed in Japanese Patent Application Nos. 1992-122257A and 1992-317650A. The process for making the disposable diaper is generally classified into a process according to which the thigh-surrounding zones of individual finished products extend in the machine direction (so-called lengthwise or end-to-end arranged process) and a process according to which the thigh-surrounding zones of individual finished products extend in the direction orthogonal to the machine direction (so-called laterally running or side-by-side arranged process). The inventions disclosed in the above-cited Applications are classified into the former process. Generally, the former process is suitable for making a so-called open-type diaper having its front and rear waist regions connected to each other immediately before actual use to meet requirements for mass-production of the diaper at desired high velocity. The latter process, on the other hand, is suitable for making a so-called pants-type or pull-on-type diaper having its front and rear waist regions previously connected to each other. The invention relating to the latter process in which a plurality of elastic members are preferably placed along each of the thigh-surrounding zones is disclosed in Japanese Patent Application No. 1991-33201A.
The above-cited Japanese Patent Application Nos. 1992-122257A and 1992-317650A disclose the process for placement of continuous elastic members associated with the leg-holes. According to this process, a continuous web as a component material for the diaper is provided along its transversely opposite side edges with adhesive zones arranged intermittently in the longitudinal direction, then elastic members associated with the respective leg-holes, each comprising a plurality of elastic elements, are fed under tension onto the respective adhesive zones and secured thereto so that the elastic members associated with the leg-holes may describe generally sinusoidal curves. According to this process of prior art, these elastic members associated with the leg-holes are forcibly traversed against tensile force of these elastic members so as to extend across the continuous web. Consequently, the elastic members associated with the leg-holes present a tensile strength higher in a generally middle zone than the remaining zone in a crotch region of the diaper.
Placement of the elastic members associated with the leg-holes in this manner causes these elastic members to present a tensile stress higher in the middle zone than in the remaining zone, resulting in that gathers formed in the middle zone of the crotch region do not easily extend as the diaper is worn. Gaps between the wearer's skin and the gathers may cause leak of body fluids. Additionally, it is likely that the diaper as a whole might shift from its proper position and a liquid-absorbent core might be twisted and deformed as the crotch region of the diaper shifts due to a movement of the wearer's thighs. These factors also may cause leak of body fluids and, in addition, might create a feeling of discomfort against the wearer. In case of a diaper provided on its side flaps on which the elastic members associated with the leg-holes are placed and these side flaps are provided, in turn, with elastic barrier flaps, there is an additional anxiety that relatively high tensile stress of the elastic members associated with the leg-holes might prevent the barrier flaps from rising as sufficiently high as expected.
It is an object of this invention to solve such problems as have been described above in disposable absorbent wearing articles such as a disposable diaper.